Quality of Life and Nonmotor Symptoms in Parkinson's Disease.

Health-related quality of life (HRQoL) is defined as "the perception and evaluation by patients themselves of the impact caused on their lives by the disease and its consequences." HRQoL is conceptualized as a combination of physical, psychological, and social well-being in the context of a particular disease. Following earlier studies revolving on the impact of the classic motor symptoms of Parkinson's disease on HRQoL, mounting evidence have been produced that nonmotor symptoms (NMS) significantly and independently contribute to worse HRQoL. This holds particularly true for such NMS such as neuropsychiatric disturbances, cognitive impairment, and fatigue, the burden of which might well exceed the effects of the motor symptoms. Nonetheless, there is very sparse evidence on how to manage these NMS and whether targeting NMS would in fact lead to an improvement of HRQoL, which calls for the need of future trials with NMS as primary outcomes.